Background & objectives: Published natural history data on late-onset of multiple sclerosis are limited. We aimed to assess the risk of attaining EDSS 6.0 among patients with late-onset (> 40 years) MS (LOMS) and young-onset (18-40 years) MS (YOMS).
Methods: This cross-sectional cohort study was conducted to identify LOMS and YOMS patients' with relapsing remitting course at MS diagnosis. Time (years) to reach sustained EDSS 6.0 was compared between LOMS and AOMS patients. Cox proportional hazards model was used to evaluate the demographic and clinical predictors of time to EDSS 6.0 in these cohorts.
Results: LOMS and YOMS cohorts comprised 99 (10.7%) and 804 (89.3%) patients respectively. Spinal cord presentation at MS onset was more common among LOMS patients (46.5% vs. 32.3%). The proportions of LOMS and YOMS patients reaching EDSS 6.0 during the follow-up period were 19.2% and 15.7% respectively. In multivariable Cox proportional hazards model, older age at MS onset (adjusted hazard ratio (aHR) = 3.96; 95% CI: 2.14-7.32; p < 0.001), male gender (aHR = 1.85; 95% CI: 1.22-2.81; p = 0.004) and spinal cord presentation at onset (aHR = 1.47; 95% CI: 0.98-2.21; p = 0.062) were significantly associated with shorter time to EDSS 6.0.
Conclusions: LOMS patients attained EDSS 6.0 in a significantly shorter period that was influenced by male gender and spinal cord presentation at MS onset.